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import Ember from 'ember'; | |
const { | |
Component, | |
computed | |
} = Ember; | |
export default Component.extend({ | |
scrollTop: 0, | |
itemCount: computed.alias('items.length'), | |
viewportHeight: computed(function () { | |
return this.get('itemCount') * this.get('rowHeight'); | |
}), | |
startIndex: computed('scrollTop', function () { | |
let startNode = Math.floor(this.get('scrollTop') / this.get('rowHeight')) - this.get('renderAhead'); | |
startNode = Math.max(0, startNode); | |
return startNode; | |
}), | |
visibleNodeCount: computed('startIndex', function () { | |
let count = Math.ceil(this.get('rootHeight') / this.get('rowHeight')) + 2 * this.get('renderAhead'); | |
count = Math.min(this.get('itemCount') - this.get('startIndex'), count); | |
return count; | |
}), | |
visibleItems: computed('startIndex', 'visibleNodeCount', function () { | |
return this.get('items').slice( | |
this.get('startIndex'), | |
this.get('startIndex') + this.get('visibleNodeCount') | |
); | |
}), | |
offsetY: computed('startIndex', function () { | |
return this.get('startIndex') * this.get('rowHeight'); | |
}), | |
spacerStyle: computed('offsetY', function () { | |
return ` | |
will-change: transform; | |
transform: translateY(${this.get('offsetY')}px) | |
`; | |
}), | |
viewportStyle: computed(function () { | |
return ` | |
will-change: transform; | |
overflow: hidden; | |
height: ${this.get('viewportHeight')}px; | |
position: relative; | |
`; | |
}), | |
rootStyle: computed(function () { | |
return ` | |
overflow: auto; | |
height: ${this.get('rootHeight')}px; | |
`; | |
}), | |
handleScroll() { | |
requestAnimationFrame(() => { | |
this.set('scrollTop', this.get('$root.scrollTop')); | |
}); | |
}, | |
init() { | |
this._super(...arguments); | |
this.set('handleScroll', this.get('handleScroll').bind(this)); | |
}, | |
didInsertElement() { | |
this._super(...arguments); | |
this.set('$root', this.element.querySelector('.root')); | |
this.get('$root').addEventListener('scroll', this.get('handleScroll'), { passive: true }); | |
}, | |
willDestroyElement() { | |
this._super(...arguments); | |
this.get('$root').removeEventListener('scroll', this.get('handleScroll')); | |
} | |
}) |
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import Controller from '@ember/controller'; | |
export default class ApplicationController extends Controller { | |
items = new Array(100000) | |
.fill(null) | |
.map((item, index) => "Item " + (index + 1)); | |
} |
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body { | |
margin: 12px 16px; | |
font-family: 'Helvetica Neue', Helvetica, Arial, sans-serif; | |
font-size: 12pt; | |
} | |
* { | |
box-sizing: border-box; | |
} | |
.viewport { | |
background: #fefefe; | |
} | |
.spacer > div { | |
height: 30px; | |
line-height: 30px; | |
border: 1px solid #f5f5f5; | |
} |
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{ | |
"version": "0.17.1", | |
"EmberENV": { | |
"FEATURES": {}, | |
"_TEMPLATE_ONLY_GLIMMER_COMPONENTS": false, | |
"_APPLICATION_TEMPLATE_WRAPPER": true, | |
"_JQUERY_INTEGRATION": true | |
}, | |
"options": { | |
"use_pods": false, | |
"enable-testing": false | |
}, | |
"dependencies": { | |
"jquery": "https://cdnjs.cloudflare.com/ajax/libs/jquery/3.5.1/jquery.js", | |
"ember": "2.16.2", | |
"ember-template-compiler": "2.16.2", | |
"ember-testing": "2.16.2" | |
}, | |
"addons": { | |
"@glimmer/component": "1.0.0" | |
} | |
} |
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